add new solutions

solutions/2/q205/solution.go

@@ -0,0 +1,26 @@
+package q205
+
+func isIsomorphic(s string, t string) bool {
+	if len(s) != len(t) {
+		return false
+	}
+
+	ab := make(map[byte]byte, 256)
+	ba := make(map[byte]byte, 256)
+	for i := range len(s) {
+		if b, ok := ab[s[i]]; ok {
+			if t[i] != b {
+				return false
+			}
+		} else {
+			if _, ok := ba[t[i]]; ok {
+				return false
+			}
+			ab[s[i]] = t[i]
+			ba[t[i]] = s[i]
+		}
+	}
+	return true
+}
+
+var _ = isIsomorphic

solutions/2/q219/solution.go

@@ -0,0 +1,18 @@
+package q219
+
+func containsNearbyDuplicate(nums []int, k int) bool {
+	seen := make(map[int]struct{}, k)
+
+	for i, num := range nums {
+		if _, ok := seen[num]; ok {
+			return true
+		}
+		seen[num] = struct{}{}
+		if i >= k {
+			delete(seen, nums[i-k])
+		}
+	}
+	return false
+}
+
+var _ = containsNearbyDuplicate

solutions/2/q290/solution.go

@@ -0,0 +1,30 @@
+package q290
+
+import "strings"
+
+func wordPattern(pattern string, s string) bool {
+	index := map[byte]string{}
+	invIndex := map[string]struct{}{}
+
+	fields := strings.Fields(s)
+	if len(fields) != len(pattern) {
+		return false
+	}
+
+	for i, word := range fields {
+		if w, ok := index[pattern[i]]; ok {
+			if w != word {
+				return false
+			}
+		} else {
+			if _, ok := invIndex[word]; ok {
+				return false
+			}
+			index[pattern[i]] = word
+			invIndex[word] = struct{}{}
+		}
+	}
+	return true
+}
+
+var _ = wordPattern